U.S. patent application number 12/447334 was filed with the patent office on 2010-03-18 for electrochemical device.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Kazuaki Fukushima, Shuji Goto, Tetsuro Kusamoto, Sayaka Nanjo.
Application Number | 20100068562 12/447334 |
Document ID | / |
Family ID | 39324461 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100068562 |
Kind Code |
A1 |
Fukushima; Kazuaki ; et
al. |
March 18, 2010 |
ELECTROCHEMICAL DEVICE
Abstract
An electrochemical device capable of improving arrangement
efficiency of bonded bodies and securing favorable sealing
characteristics is provided. An electrolyte membrane 11 has a
reaction region 11A sandwiched between a fuel electrode 12 and an
oxygen electrode 13 and a peripheral region 11B exposed from
between the fuel electrode 12 and the oxygen electrode 13. A
connection member 20 has a bent section 23 between two flat
sections 21 and 22. Since an adhesive layer 14 is provided in the
peripheral section 11B of the electrolyte membrane 11, and the bent
section 23 of the connection member 20 is bonded to the adhesive
layer 14, arrangement efficiency of a bonded body 10 is improved,
and favorable sealing characteristics are secured. The adhesive
layer 14 has a structure in which a first contact layer having high
adhesion to the electrolyte membrane 11, a barrier layer, a
strength retention layer, and a second contact layer having high
adhesion to the connection member 20 are sequentially laminated.
Since a connection-member-side adhesive layer is provided on the
bent section 23 of the connection member 20, adhesion strength can
be further improved.
Inventors: |
Fukushima; Kazuaki;
(Kanagawa, JP) ; Goto; Shuji; (Kanagawa, JP)
; Nanjo; Sayaka; (Kanagawa, JP) ; Kusamoto;
Tetsuro; (Kanagawa, JP) |
Correspondence
Address: |
K&L Gates LLP
P. O. BOX 1135
CHICAGO
IL
60690
US
|
Assignee: |
SONY CORPORATION
Tokyo
JP
|
Family ID: |
39324461 |
Appl. No.: |
12/447334 |
Filed: |
October 18, 2007 |
PCT Filed: |
October 18, 2007 |
PCT NO: |
PCT/JP2007/070316 |
371 Date: |
April 27, 2009 |
Current U.S.
Class: |
429/524 ;
429/481; 429/535 |
Current CPC
Class: |
H01M 8/0247 20130101;
H01M 8/1009 20130101; H01M 8/242 20130101; Y02E 60/50 20130101;
H01M 8/028 20130101; H01M 8/0273 20130101; H01M 8/1011 20130101;
Y02E 60/522 20130101; H01M 8/2418 20160201; G01N 27/406 20130101;
Y02E 60/523 20130101; H01M 2008/1095 20130101; H01M 8/1013
20130101 |
Class at
Publication: |
429/12 |
International
Class: |
H01M 8/02 20060101
H01M008/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2006 |
JP |
2006-292734 |
Claims
1-7. (canceled)
8. An electrochemical device comprising linked bonded bodies in
which a pair of electrodes are oppositely arranged with an
electrolyte membrane in between in an in-plane direction by a
conductive connection member, wherein the electrolyte membrane has
a reaction region sandwiched between the pair of electrodes and a
peripheral region that is exposed from the pair of electrodes and
that is provided with an adhesive layer, and the connection member
has two flat sections and a bent section provided between the two
flat sections, the respective two flat sections are contacted with
one of the pair of electrodes of adjacent bonded bodies, and the
bent section is bonded to the adhesive layer.
9. The electrochemical device according to claim 8, wherein the
adhesive layer includes a first contact layer contacted with the
electrolyte membrane.
10. The electrochemical device according to claim 9, wherein the
adhesive layer includes a second contact layer on a side opposite
to the electrolyte membrane with respect to the first contact
layer.
11. The electrochemical device according to claim 10, wherein the
adhesive layer includes at least one of a barrier layer and a
strength retention layer between the first contact layer and the
second contact layer.
12. The electrochemical device according to claim 8, wherein a
connection-member-side adhesive layer is provided on the bent
section of the connection member.
13. The electrochemical device according to claim 8, wherein the
bonded bodies are arranged in a two-dimensional arrangement
composed of a plurality of lines and columns, and the connection
member links the bonded bodies in column direction at one end or
both ends in line direction, and links the bonded bodies in the
line direction at locations other than the one end or the both ends
in line direction.
14. The electrochemical device according to claim 8 wherein the
electrochemical device is a fuel cell in which a fuel electrode and
an oxygen electrode are oppositely arranged with the electrolyte
membrane in between.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electrochemical device
linking a plurality of bonded bodies in which a pair of electrodes
are oppositely arranged with an electrolyte membrane in between,
and particularly to an electrochemical device suitable for a fuel
cell, a fuel sensor and the like.
BACKGROUND ART
[0002] Currently, various primary batteries and secondary batteries
are used as an electric source of electronic devices. As one of
indicators exhibiting characteristics of these batteries, there is
an energy density. The energy density is an energy cumulative
amount per unit mass of a battery.
[0003] As miniaturization and high performance of the electronic
devices have been developed in recent years, a high capacity and a
high output of the electric source, in particular, the high
capacity of the electric source is increasingly necessitated. Thus,
it has been hard to supply a sufficient energy to drive the
electronic devices with the use of the conventional primary
batteries and the conventional secondary batteries. Therefore, it
is urgently needed to develop a battery having a higher energy
density. Fuel cells attract attention as one of candidates having a
higher energy density.
[0004] The fuel cell has a structure in which an electrolyte is
arranged between an anode (fuel electrode) and a cathode (oxygen
electrode). A fuel is supplied to the fuel electrode, and air or
oxygen is supplied to the oxygen electrode. This results in redox
reaction in which the fuel is oxidized by oxygen in the fuel
electrode and the oxygen electrode, and part of chemical energy of
the fuel is converted to electric energy and extracted.
[0005] Various types of fuel cells have been already proposed and
experimentally produced, and part thereof is practically used.
These fuel cells are categorized into an Alkaline Fuel Cell (AFC),
a Phosphoric Acid Fuel Cell (PAFC), a Molten Carbonate Fuel Cell
(MCFC), a Solid Electrolyte Fuel Cell (SOFC), a Polymer Electrolyte
Fuel Cell (PEFC) and the like according to the electrolyte
used.
[0006] FIG. 12 illustrates a structure of a conventional PEFC. The
PEFC has a bonded body (MEA; Membrane Electrolyte Assembly) 110 in
which a fuel electrode 112 and an oxygen electrode 113 are arranged
with an electrolyte membrane 111 composed of a solid polymer
electrolyte in between. A unit in which the bonded body 110 is
sandwiched between separators (not illustrated) configures one unit
cell.
[0007] A voltage capable of being extracted from the one unit cell
is about 0.3 V to 0.8 V, and this voltage is not enough to be used
singly. Therefore, in general, a fuel cell stack in which a
plurality of unit cells are stacked is used. Meanwhile, for the use
of mobile devices, a thin structure is preferred, and thus it is
often the case that a plane stacked structure in which a plurality
of unit cells are two-dimensionally arranged in line or in a
plurality of lines, and such a plurality of unit cells are
electrically connected in series is adopted.
[0008] In the two-dimensionally arranged bonded bodies 110, the
electron transfer distance between adjacent two bonded bodies 110
is larger than that in vertically stacked bonded bodies. Thus, the
arrangement and the current collection structure of the bonded
bodies 110 are important to decrease resistance of all cells. That
is, as illustrated in FIG. 13(A), in the case where the bonded
bodies 110 are vertically stacked with a separator 120 in between,
average transfer distance L is small and electron transfer
cross-sectional area S is large, and thus electric resistance
generated in the separator 120 can be kept small, resulting in an
advantageous structure for flowing a large current. Meanwhile, as
illustrated in FIG. 13(B), in the case where the bonded bodies 110
are two-dimensionally arranged by linking the bonded bodies 110 by
a connection plate 130, by contraries, the average transfer
distance L is large and the electron transfer cross-sectional area
S is small, resulting in a disadvantageous structure for extracting
a large current (for example, refer to Non Patent Document 1).
[0009] Conventionally, for example, the following structure has
been proposed. In the structure, electricity generated in a unit
cell is collected by using a Z-shaped connection plate, and
adjacent unit cells are electrically connected in series, and
thereby the electron transfer distance is shortened (for example,
refer to Patent Document 1). [0010] Non Patent Document 1:
"Function chemistry of electron and ion Vol. 4: All about Polymer
Electrolyte Fuel Cell," Edited by Hiroyuki Uchida and three
authors, NTS Inc., 2003, pp. 143-145) [0011] Patent Document 1:
Japanese Unexamined Patent Application Publication No.
2002-56855
DISCLOSURE OF INVENTION
[0012] In the conventional structure, however, there has been a
problem that since the distance between bonded bodies is large, the
electrode area to the entire fuel cell is small, and the
arrangement efficiency of the bonded bodies is lowered. This is
because when the Z-shaped connection plate is provided, it is
necessary to provide sealing between an end of the bonded body and
the Z-shaped connection plate and provide sealing at the outer
peripheral section of the entire fuel cell.
[0013] The sealing between the bonded body and the Z-shaped
connection plate has been provided by physically adhering a sealing
material such as PPS (polyphenylene sulfide) and silicone rubber
sandwiching an electrolyte membrane to the Z-shaped connection
plate by a fastening screw or the like. Thus, there has been a
problem that the Z-shaped connection plate needs strength so that
the Z-shaped connection plate can resist deformation due to
tightening the screw or the like, so the thickness of the Z-shaped
connection plate is needed to be thick, and it is hard to obtain a
thin device. Further, it is hard to secure sufficient sealing
characteristics by using a small number of fastening screws. In
practice, it is necessary to fill in a sealing member between the
bonded body and the Z-shaped connection plate, and it is often the
case that the process are complicated.
[0014] In view of the foregoing problems, it is an object of the
present invention to provide an electrochemical device capable of
improving arrangement efficiency of bonded bodies and securing
favorable sealing characteristics.
[0015] In the electrochemical device according to the present
invention, bonded bodies in which a pair of electrodes are
oppositely arranged with an electrolyte membrane in between are
linked in the in-plane direction by a conductive connection member.
The electrolyte membrane has a reaction region sandwiched between
the pair of electrodes and a peripheral region that is exposed from
the pair of electrodes and that is provided with an adhesive layer.
The connection member has two flat sections and a bent section
provided between the two flat sections. The respective two flat
sections are contacted with one of the pair of electrodes of
adjacent bonded bodies. The bent section is bonded to the adhesive
layer.
[0016] According to the electrochemical device of the present
invention, the adhesive layer is provided in the peripheral region
of the electrolyte membrane, and the adhesive layer is adhered to
the bent section of the connection member. Thus, the electrolyte
membrane and the connection member are more tightly adhered by
chemical adhesion, and favorable sealing characteristics can be
secured. Therefore, differently from the conventional art, it is
not necessary to fill in a sealing member between the bonded body
and the connection member, the electrode area in the entire fuel
cell can be increased, and arrangement efficiency of the bonded
bodies can be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a cross sectional view illustrating a structure of
a fuel cell as an electrochemical device according to an embodiment
of the present invention.
[0018] FIG. 2 is a plan view illustrating a structure viewed from
an oxide electrode 13 side of the fuel cell illustrated in FIG.
1.
[0019] FIG. 3 is a cross sectional view illustrating a structure of
the bonded body illustrated in FIG. 1.
[0020] FIG. 4 is a cross sectional view illustrating a structure of
the connection member illustrated in FIG. 1.
[0021] FIG. 5 is a cross sectional view illustrating a structure of
the adhesive layer illustrated in FIG. 1.
[0022] FIG. 6 are cross sectional views illustrating a method of
manufacturing the fuel cell illustrated in FIG. 1 in order of
steps.
[0023] FIG. 7 are cross sectional views illustrating steps
following FIG. 6.
[0024] FIG. 8 are cross sectional views illustrating steps
following FIG. 7.
[0025] FIG. 9 is a cross sectional view illustrating a step
following FIG. 8.
[0026] FIG. 10 is a plan view illustrating a structure viewed from
the oxide electrode 13 side of a fuel cell as an electrochemical
device according to a modified example of the present
invention.
[0027] FIG. 11 is an exploded plan view of the fuel cell
illustrated in FIG. 10.
[0028] FIG. 12 is a cross sectional view illustrating a structure
of a conventional fuel cell.
[0029] FIG. 13 are cross sectional views for explaining a vertical
stacked structure and a plane stacked structure by comparison.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0030] An embodiment of the present invention will be hereinafter
described in detail.
[0031] FIG. 1 and FIG. 2 illustrate a structure of a fuel cell as
an electrochemical device according to an embodiment of the present
invention. The fuel cell is a Direct Methanol Fuel Cell (DMFC) used
for, for example, a mobile device such as a mobile phone and a PDA
(Personal Digital Assistant) or a notebook PC (Personal Computer).
The fuel cell has a plane stacked structure in which a plurality of
(for example, three) bonded bodies 10 are linked in the in-plane
direction by a conductive connection member 20. A terminal 30 is
attached to the both endmost bonded bodies 10. On both faces of the
linked bonded bodies 10, a pair of insulating plates 40 are fixed
by a fastening screw 41. On the outer side of one of the insulating
plates 40, a fuel supply system 50 is provided. In FIG. 2, the
insulating plate 40 is omitted.
[0032] As illustrated in FIG. 3, the bonded body 10 has a fuel
electrode 12 and an oxygen electrode 13 that are oppositely
arranged with an electrolyte membrane 11 in between.
[0033] The electrolyte membrane 11 has a reaction region 11A
sandwiched between the fuel electrode 12 and the oxygen electrode
13 and a peripheral region 11B exposed from between the fuel
electrode 12 and the oxygen electrode 13. The electrolyte membrane
11 is made of, for example, a proton conductive material having a
sulfonic acid group (--SO.sub.3H). As the proton conductive
material, a polyperfluoroalkyl sulfonic acid proton conductive
material (for example, "Nafion (registered trademark) produced by
DuPont), a hydrocarbon proton conductive material such as polyimide
sulfonic acid, a fullerene proton conductive material and the like
are included.
[0034] The fuel electrode 12 and the oxygen electrode 13 have a
structure in which, for example, a catalyst layer containing a
catalyst such as platinum (Pt) and ruthenium (Ru) is formed on a
current collector made of, for example, a carbon paper or the like.
The catalyst layer is made of, for example, a layer in which a
support substance such as carbon black supporting the catalyst is
dispersed in the polyperfluoroalkyl sulfonic acid proton conductive
material.
[0035] As illustrated in FIG. 4, the connection member 20 has a
bent section 23 between two flat sections 21 and 22. The flat
section 21 is contacted with the fuel electrode 12 of one bonded
body 10, and the flat section 22 is contacted with the oxygen
electrode 13 of another bonded body 10 adjacent to the foregoing
one bonded body 10. Thereby, the connection member 20 electrically
connects the two adjacent bonded bodies 10 in series, and also has
a function as a current collector to collect electricity generated
in each bonded body 10. Such a connection member 20 has a thickness
of 150 .mu.m, for example, and is made of copper (Cu), nickel (Ni),
titanium (Ti), or stainless steel (SUS), and may be plated by gold
(Au), platinum (Pt) or the like. Further, the connection member 20
has an aperture (not illustrated) to respectively supply a fuel and
air to the fuel electrode 12 and the oxygen electrode 13, and is
made of, for example, a mesh such as an expanded metal, a punching
metal or the like. The bent section 23 may be previously bent
adjusting to the thickness of the bonded body 10. Otherwise, in the
case where the connection member 20 is made of a flexible material
such as a mesh having a thickness of 200 .mu.m or less, the bent
section 23 may be formed by being bent in the manufacturing
step.
[0036] Further, in this embodiment, an adhesive layer 14 is
provided in the peripheral region 11B of the electrolyte membrane
11. The bent section 23 of the connection member 20 is bonded to
the adhesive layer 14. Thereby, in this fuel cell, favorable
sealing characteristics can be secured while improving arrangement
efficiency of the bonded bodies 10.
[0037] The adhesive layer 14 has, for example, a structure in which
a first contact layer 14A and a second contact layer 14B are
laminated sequentially from the electrolyte membrane 11 side.
[0038] The first contact layer 14A is for obtaining adhesion to the
electrolyte membrane 11. The first contact layer 14A has, for
example, a thickness of 50 .mu.m, and is made of a resin having
high adhesiveness to the electrolyte membrane 11, specifically a
resin obtained by modifying polyethylene, polypropylene or the like
by an acid, an acid anhydride, an acid ester, metallocene, a
hydroxyl group or the like; or a resin having, as a functional
group, a basic substituent group such as imidazole, pyridine, and
amine capable of being bonded to the sulfonic acid group of the
electrolyte membrane 11 by interaction on the surface thereof. As a
component material of the first contact layer 14A, for example,
polyvinyl alcohol or a copolymer thereof is included.
[0039] The second contact layer 14B is for obtaining favorable
bonding to the connection member 20. The second contact layer 14B
has, for example, a thickness of 10 .mu.m, and is made of a resin
having high adhesion and high heat sealing characteristics to the
metal composing the connection member 20, specifically a resin
obtained by modifying polyethylene, polypropylene or the like by an
acid, an acid anhydride, an acid ester, metallocene, a hydroxyl
group or the like.
[0040] Further, as illustrated in FIG. 5, the adhesive layer 14
preferably has a barrier layer 14C and a strength retention layer
14D between the first contact layer 14A and the second contact
layer 14B.
[0041] The barrier layer 14C is for preventing permeation of
methanol or hydrogen as a fuel and gas such as oxygen and moisture
vapor. The barrier layer 14C has, for example, a thickness of 8
.mu.m, and is made of an aluminum (Al) foil, or an inorganic
evaporated layer of silicon dioxide (silica: SiO.sub.2), aluminum
(A), aluminum oxide (alumina) or the like.
[0042] The strength retention layer 14D is for preventing thermal
deformation and melt flow in bonding to the connection member 20,
and for improving mechanical strength of the bonding section to the
connection member 20. The strength retention layer 14D has, for
example, a thickness of 12 .mu.m, and is made of a polyester resin
such as PET (polyethylene terephthalate) or nylon.
[0043] The bent section 23 of the connection member 20 is
preferably provided with a connection-member-side adhesive layer
24, since thereby the adhesion strength can be further improved. In
particular, such a connection-member-side adhesive layer 24 is
suitable in the case where the connection member 20 is made of a
mesh such as an expanded metal and uniformly has aperture sections.
The connection-member-side adhesive layer 24 is formed, for
example, similarly to the second contact layer 14B.
[0044] The terminal 30 illustrated in FIG. 1 and FIG. 2 is formed
similarly to the connection member 20.
[0045] The insulating plate 40 illustrated in FIG. 1 has a function
to retain the physical strength of the linked bonded bodies 10, a
function to secure contact between the connection member 20 and the
fuel electrode 12/the oxygen electrode 13, a function to prevent
electric short circuit between adjacent bonded bodies 10 and the
like. The insulating plate 40 desirably has a certain strength and
an aperture (not illustrated) to supply fuel to the fuel electrode
12. Such an insulating plate 40 has, for example, a thickness of
1.5 mm, and is made of aluminum (Al) provided with alumite
treatment, super engineering plastic or engineering plastic such as
polyphenylene sulfide and polyether ether ketone, ceramics, or a
metal material such as stainless steel provided with insulating.
The insulating plate 40 may be fixed by a caulking structure or
adhesion by an adhesive agent, in addition to the fastening screw
41.
[0046] The fuel supply system 50 illustrated in FIG. 1 supplies a
liquid fuel including methanol or the like to the fuel electrode 12
through the aperture provided in the insulating plate 40 and the
connection member 20 (neither thereof illustrated). The oxygen
electrode 13 is communicated with outside through the apertures
provided in the insulating plate 40 and the connection member 20
(neither thereof illustrated) and is supplied with air, that is,
oxygen by natural ventilation.
[0047] In addition, though not illustrated, the outer peripheral
section of the fuel cell is sealed by adhering the adhesive layer
14 to the insulating plate 40 on the fuel electrode 12 side or the
insulating plate 40 on the oxygen electrode 13 side to prevent the
entry of air from a side face and fuel leakage. In addition, in the
case where the thickness of the adhesive layer 14 is not
sufficient, it is possible to address it by increasing the number
of layers of the adhesive layer 14 and increasing the thickness
thereof. Further, instead of the adhesive layer 14, or in addition
to the adhesive layer 14, a sealing member such as silicone rubber
may be provided only in the outer peripheral section.
[0048] The fuel cell can be manufactured, for example, as
follows.
[0049] FIGS. 6 to 9 illustrate a method of manufacturing this fuel
cell in order of steps. First, the electrolyte membrane 11 that has
plane dimensions of, for example, 20 mm.times.40 mm and is made of
the foregoing material is sandwiched between the fuel electrode 12
and the oxygen electrode 13 that have, for example, plane
dimensions of 15 mm.times.35 mm and are made of the foregoing
material. The resultant is thermally compression-bonded for 15
minutes at 130 deg C. under a pressure of 0.5 kN, for example.
Thereby, the fuel electrode 12 and the oxygen electrode 13 are
bonded to the electrolyte membrane 11 to form the bonded body 10.
At this time, in the electrolyte membrane 11, the reaction region
11A sandwiched between the fuel electrode 12 and the oxygen
electrode 13 and the peripheral region 11B exposed from between the
fuel electrode 12 and the oxygen electrode 13 are formed.
[0050] Next, in the peripheral region 11B of the electrolyte
membrane 11, the first contact layer 14A, the barrier layer 14C,
the strength retention layer 14D, and the second contact layer 14B
made of the foregoing materials are sequentially laminated to form
the adhesive layer 14. The first contact layer 14A, the barrier
layer 14C, the strength retention layer 14D, and the second contact
layer 14B may be previously laminated by thermal bonding or dry
lamination using an adhesive agent or the like before being
laminated over the electrolyte membrane 11. Further, as the first
contact layer 14A and the second contact layer 14B, a film-like or
sheet-like resin made of the foregoing material may be used.
[0051] Further, the connection member 20 made of the foregoing
material is prepared. On the bent section 23 thereof, the
connection-member-side adhesive layer 24 made of the foregoing
material is provided.
[0052] Subsequently, as illustrated in FIG. 6(A) and FIG. 6(B), the
adhesive layer 14 of the electrolyte membrane 11 is
compression-bonded to the connection-member-side adhesive layer 24
of the bent section 23 of the connection member 20 for 10 seconds
at 170 deg C. Similarly, as illustrated in FIG. 7(A) and FIG. 7(B),
three bonded bodies 10 are linked in line by the connection member
20, and the terminal 30 is attached to the both endmost bonded
bodies 10. This step can be performed by using an ultrasonic
welder.
[0053] After that, as illustrated in FIG. 8(A) and FIG. 8(B), the
insulating plate 40 is thermally compression-bonded to the fuel
electrode 12 of the linked bonded bodies 10 for 30 seconds at 170
deg C., and thereby the fuel electrode 12 is shielded from the air.
This step may be performed by using an ultrasonic welder. Further,
as illustrated in FIG. 9, the insulating plate 40 is also arranged
on the oxygen electrode 13, and the two insulating plates 40 are
fixed by the fastening screw 41. Finally, the fuel supply system 50
is attached to the outer side of the insulating plate 40 on the
fuel electrode 12 side. Accordingly, the fuel cell illustrated in
FIG. 1 and FIG. 2 is completed. In addition, the fuel cell was
actually fabricated by this manufacturing method, and the output
was examined. Then, an output current of 900 mA at a voltage of 1.0
V was obtained (900 mW).
[0054] In the fuel cell, the fuel is supplied to the fuel electrode
12, and protons and electrons are generated by reaction. The
protons are transferred to the oxygen electrode 13 through the
electrolyte membrane 11, and are reacted with electrons and oxygen
to generate water. In the fuel cell, the adhesive layer 14 is
provided in the peripheral region 11B of the electrolyte membrane
11, and the adhesive layer 14 is adhered to the bent section 23 of
the connection member 20. Thus, the electrolyte membrane 11 and the
connection member 20 are tightly adhered by chemical adhesion.
Therefore, differently from the conventional art, it is not
necessary to fill in a sealing member between the bonded body and
the connection member. Accordingly, the distance between the bonded
bodies 10 is reduced, the bonded bodies 10 are connected in series
with small electric resistance, and the output current is
increased.
[0055] As described above, according to this embodiment, the
adhesive layer 14 is provided in the peripheral region 11B of the
electrolyte membrane 11, and the adhesive layer 14 is adhered to
the bent section 23 of the connection member 20. Thus, the
electrolyte membrane 11 and the connection member 20 are tightly
adhered by chemical adhesion, and favorable sealing characteristics
can be secured. Therefore, differently from the conventional art,
it is not necessary to fill in a sealing member between the bonded
body and the connection member, the electrode area in the entire
fuel cell can be increased, and arrangement efficiency of the
bonded bodies 10 can be improved.
[0056] In addition, in the foregoing embodiment, the description
has been given of a case where the adhesive layer 14 has a
structure in which the first contact layer 14A, the barrier layer
14C, the strength retention layer 14D, and the second contact layer
14B are laminated sequentially from the electrolyte membrane 11
side. However, it is enough that the adhesive layer 14 has at least
the first contact layer 14A, and the barrier layer 14C, the
strength retention layer 14D, and the second contact layer 14B may
be provided according to needs.
[0057] Further, the lamination order of the barrier layer 14C and
the strength retention layer 14D is not particularly limited. For
example, it is possible that the first contact layer 14A, the
strength retention layer 14D, the barrier layer 14C, and the second
contact layer 14B may be laminated sequentially from the
electrolyte membrane 11 side.
[0058] Further, both the barrier layer 14C and the strength
retention layer 14D may be provided, or only one thereof may be
provided. Further, the first contact layer 14A or the second
contact layer 14B may have the function of the barrier layer 14C or
the strength retention layer 14D.
Modified Example
[0059] FIG. 10 illustrates a structure of a fuel cell as an
electrochemical device according to a modified example of the
present invention. The fuel cell has the same structure as that of
the fuel cell described in the foregoing embodiment except that six
bonded bodies 10 are arranged in a two-dimensional arrangement
composed of three columns by two lines. The fuel cell according to
the modified example of the present invention can be manufactured
similarly to the fuel cell described in the foregoing embodiment.
Therefore, the same reference symbols as those of the fuel cell
described in the foregoing embodiment are affixed to the
corresponding elements.
[0060] As illustrated in the exploded view of FIG. 11, these six
bonded bodies 10 are linked in column direction B at one end in
line direction A, and are linked in the line direction A at the
locations other than the foregoing one end, and thereby these six
bonded bodies 10 are linked in a state of so-called U-shape.
Thereby, in this modified example, degree of freedom of arrangement
method in the plane stacked structure is increased, and a large
voltage can be extracted by using many bonded bodies 10. For
example, in the case where the number of lines in the
two-dimensional arrangement is increased to 3 or more, bonded
bodies 10 are repeatedly linked in the column direction B at one
end in one line and at the other end in the subsequent line, and
are linked in a meander shape as a whole. Thereby, no matter how
mach the number of bonded bodies 10 is increased, the bonded bodies
10 can be electrically connected in series. Further, the bonded
bodies 10 may be linked in spirals or in whorl. In addition, six
bonded bodies 10 having the fuel electrode 12 and the oxygen
electrode 13 with dimensions of 15 mm.times.15 mm were actually
fabricated, the fuel cell in which the six bonded bodies 10 were
linked in a state of U-shape was actually fabricated as illustrated
in FIG. 10 and FIG. 11, and the output was examined. Then, an
output current of 400 mA at a voltage of 2.0 V was obtained (800
mW), and the degree of freedom of arrangement method was
confirmed.
[0061] The present invention has been described with reference to
the embodiment. However, the present invention is not limited to
the foregoing embodiment, and various modifications may be made.
For example, in the foregoing embodiment, the specific description
has been given of the structures of the electrolyte membrane 11,
the fuel electrode 12, and the oxygen electrode 13. However, the
electrolyte membrane 11, the fuel electrode 12, and the oxygen
electrode 13 may have other structure, or may be made of other
material.
[0062] Further, for example, the adhesion method and the adhesion
conditions such as the heating temperature, the pressure, and the
time or the like are not limited to those described in the
foregoing embodiment. Other adhesion method and other adhesion
conditions may be adopted. For example, in the foregoing
embodiment, after the adhesive layer 14 is formed in the peripheral
region 11B of the electrolyte membrane 11, the adhesive layer 14 is
adhered to the connection member 20. However, it is possible that
after the connection member 20 and the adhesive layer 14 are
adhered to each other, the adhesive layer 14 is thermally adhered
to the electrolyte membrane 11.
[0063] Further, in the foregoing embodiment, air supply to the
oxygen electrode 13 is implemented by natural ventilation. However,
air may be forcibly supplied by utilizing a pump or the like. In
this case, instead of air, oxygen or gas containing oxygen may be
supplied.
[0064] In addition, the present invention is applicable to not only
the DMFC, but also other type of fuel cell such as a Polymer
Electrolyte Fuel Cell using hydrogen as a fuel, a Direct Ethanol
Fuel Cell, and a Dimethyl Ether Fuel Cell.
[0065] Furthermore, in the foregoing embodiment, the description
has been given of the fuel cell as an electrochemical device.
However, in addition to the fuel cell, the present invention is
applicable to other electrochemical device such as a capacitor and
a fuel sensor.
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